The Sony control has a normal stacked pot with a tiny DC servo motor hanging
off the end. You can probably get it as a replacement part, but it won't be
cheap. There are probably other consumer systems with this kind of pot in it.

And wasn't the whole point of a rotary encoder the fact that it didn't HAVE
a 'home' position? If you want a powered control, why not use an R/C servo
with a low gear ratio so it can be 'back driven' or with a friction clutch
and continous motion (like the modified Paralax robot servo).

And if you used a PIC with comparator inputs (16F87xA series) you'd only
need 4 pins since you could tri-state the drive pins when you're not
driving the motor. Just be sure to have zener clamps on the motor coils
so that it's 'childproof'.

R

Pic Dude wrote:
>
> My all-in-one Sony mini component system does that (it's
> about 14 years old).  I don't think it's a rotary encoder
> cause it has a definite start and end, and has no detents
> (very smooth).  But altering the volume on the remote will
> change the physical position of the rotary knob.  Has a
> cool little LED on it too, to indicate the setting/position.
>
> Cheers,
> -Neil.
>
> -----Original Message-----
> From: pic microcontroller discussion list
> [mailto:PICLIST@MITVMA.MIT.EDU]On Behalf Of Bob Ammerman
> Sent: Friday, June 28, 2002 7:06 AM
> To: PICLIST@MITVMA.MIT.EDU
> Subject: Re: [EE]: stepper "digital" knob viability
>
> >And what would be really cool using a stepper motor is when you power up
> the project, the control 'moves' back to the last >stored position nice and
> smooth...
>
> Or when  you use the infrared remote, the control tracks the action of the
> remote.

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